1. Field of the Invention
The present invention relates to a device for releasing a volatile substance into the environment in a controlled manner. In particular, this invention contains the volatile substance to prevent its spilling or oozing and provides a way of releasing multicomponent substances in a uniform, continuous manner.
Many consumer products such as room deodorizers, insecticides, germicides, fragrances and the like are volatile and may be released and dispersed in an area to be treated merely by being exposed therein. Devices for dispensing these products are available in many forms such as liquid and wick systems, blotter systems and gel systems. However, the volatile substance may be subject to spillage, oozing or waste in each of these systems.
2. Description of the Prior Art
Various devices and methods for containing a volatile substance and for controlling the release of vapor from the substance are presently known. For example, U.S. Pat. No. 3,770,199 (Hoek et al.) discloses a device for the controlled emission of vapors which has an inner tubular or box-shaped member telescopically arranged in a second tubular box-shaped outer member so that the inner member may be entirely or partially sealed by the outer member. A porous container, preferably made of polyethylene, is mounted within the inner member and may be filled with an active substance. The inner member may be either apertured or also made of a porous material such as polyethylene. When the inner member is open outwardly of the outer member, the liquid active substance is vaporized inside the container and permeates through both the container and the inner member. This device operates in a fashion similar to wick devices in that the rate of volatilization of the substance may be controlled by the amount of inner member, or wick, exposed from the outer member.
U.S. Pat. No. 2,988,284 (Smith) discloses a device which includes a block made from a substance such as wood, cellulose, fiber, pulp, filament, silicate, gum, plastic or the like, which is impregnated with a fragrance and is hermetically sealed in an air-tight vapor impermeable coating. A hole or holes are drilled into the block through the coating and fragrance is emitted therefrom. Vaporization of the fragrance is controlled by the relatively small exposed surface area of the hole compared to the volume of the entire block.
U.S. Pat. No. 3,685,734 (Paciorek et al.) discloses a controlled fragrance release device which includes a substrate layer on which a layer of vinyl plastisol resin containing an essential oil or other volatile substance is coated. A cover ply is placed over the resin layer to contain the volatile substance until removed.
Another approach to controlling release of volatile substances in disclosed in U.S. Pat. No. 3,216,882 (Feldt et al.) and in U.S. Pat. No. 4,035,451 (Tringali), assigned to the assignee of the present invention. The Feldt patent discloses a porous plastic film which may be impregnated with a volatile substance to be slowly released therefrom. The Tringali patent application discloses a cartridge having a support of strip material and a battery. The cartridge is adapted for use with an apparatus for inducing air flow past the support of strip material which is impregnated with a volatile substance. This support may be a gelled cellulose triacetate product made in accordance with U.S. Pat. No. 3,846,404 (Nichols).
These latter approaches to containing and controlling release of volatile substances have certain disadvantages. In particular, porous, microporous and ultramicroporous film strips are relatively expensive. Therefore, though effective to contain and release volatile substances, they are uneconomical for use in applications where large amounts of such substances are to be initially held for later volatization into an environment.
Another significant problem with each of these devices arises when a substance having several chemical components, each having a different rate of vaporization, is dispensed. Especially in the case of multicomponent fragrances when the various components volatilize at different rates, the intensity of the fragrance as well as the fragrance itself may change with time. Therefore, an initially pleasant fragrance may lose its desirable attributes.